What universal set(s) would you propose for each of the following :
(i) The set of right triangles (ii) The set of isosceles triangles

Solution:

The universal set is a collection of all elements or members of all the related sets, known as its subsets.

All the stars in a milky way galaxy is a good example of a universal set if we consider all the stars in the milky way galaxy.

When we study numbers in mathematics, we are interested in the set of natural numbers.

This basic set is considered a universal set and its subsets are even numbers, prime numbers, etc

An universal set should contain all the sets as its subsets with respect to the context of the problem. 

(i) For the set of right triangles, the universal set can be the set of triangles or the set of polygons.

(ii) For the set of isosceles triangles, 

the universal set can be the set of triangles or the set of polygons or the set of two-dimensional figures

NCERT Solutions Class 11 Maths Chapter 1 Exercise 1.3 Question 8

What universal set(s) would you propose for each of the following : (i) The set of right triangles. (ii) The set of isosceles triangles

Summary:

We are asked to find the universal set(s) that we would propose for each of the given sets. We found that
(i) For the set of right triangles, the universal set can be the set of triangles or the set of polygons.
(ii) For the set of isosceles triangles, the universal set can be the set of triangles or the set of polygons or the set of two-dimensional figures.